Surface control of gas lift valves

ABSTRACT

This invention is a method of surface control of gas lift valves through a pneumatic tube control line connecting high-pressure charging gas at surface to the valve bellows/dome of one or more valves positioned on the production tubing within an oil, gas, or water supply well. The control line transmits pressure to close the valve or relieves pressure to open the valve. This invention eliminates the requirement of pressure charging and sealing the gas lift valve bellows/dome at the shop facility as a pre-installation condition and eliminates estimating valve temperature at wellbore conditions to correctly set a valve charge pressure in a sealed chamber. One control line can be connected to multiple valves or, as an option, individual lines to each valve can be implemented. This invention applies to injection pressure operated (IPO) or production pressure operated (PPO) gas lift valves and tubing retrievable (conventional) or side pocket mandrels.

FIELD OF THE INVENTION

This invention applies to oil, gas, or water supply wells in the upstream hydrocarbon resource industry and in the municipal or agricultural water supply industries. CPC class E21B 43/122 and 43/123, methods for obtaining oil, gas, or water from wells, includes wells that require artificial lift to produce reservoir fluid and may use gas lift as the preferred method. International class E21B 43/12 and 34/10 includes gas lift wells and valves.

BACKGROUND OF THE INVENTION

Subterranean wells are drilled through an oil, gas, or water supply reservoir and cased with a string of pipe. These wells have a tubing string of pipe, inside the casing, as the conduit for production of reservoir fluids to the wellhead and into the surface facility used to treat these fluids. If the well cannot flow naturally with reservoir pressure, then artificial lift is implemented to induce production fluid flow or to increase fluid flow. One artificial lift option is gas lift which uses a high-pressure gas source at the surface, usually compressed natural gas from the production facility but can be another gas such as plant processed natural gas, nitrogen, carbon dioxide, or air. Gas lift installations use valves that are positioned on the tubing string at various depths based on the injection pressure in the casing, production fluid pressure in the tubing, and control (kill) fluid pressure used to maintain hydrostatic control of the well during wellbore equipment installation. High-pressure injection gas is provided to the casing/tubing annulus to displace the control (kill) fluid out of the annulus, through each gas lift valve to the tubing, where the mixture of gas and tubing fluid is circulated to the wellhead and onward to the surface treating facility. The gas circulates through the uppermost first valve and continues displacing annulus fluid to the next deeper second valve. When gas begins to circulate through the second valve, the first valve must close for effective gas lift. The process of displacement continues to deeper valves, requiring sequential closing of each valve as gas circulates to the next deeper valve, until a deep point of gas injection is attained. One or multiple gas lift valves may be used depending on well depth and injection gas pressure.

The gas is injected into the casing/tubing annulus, transmitted through a gas lift valve into the tubing, and merged with reservoir production fluids to reduce the density. Reduced density of the mixture will reduce pressure at the bottom of the tubing column which enhances flow from the reservoir. An option provides gas injection into the tubing, passage through the gas lift valve, and production up the casing/tubing annulus.

Gas lift valves are controlled by an internal charge pressure, which in prior art is implemented at a surface shop and sealed prior to installation in the wellbore. This method requires knowledge of temperature at valve depth and, if a different internal charge pressure is desired, then the valve must be removed from the wellbore to be reset in the shop.

BRIEF SUMMARY OF THE INVENTION

This invention provides surface control of the closing mechanism for each valve, which is the pneumatic tube control line with charging gas linked to the internal bellows/dome of the valve from the source at the surface (an option is one control line for each valve). Pressure is raised in the control line to close each valve, and because each is at a different depth, they will close in sequence by adjusting the control line pressure at the surface. When a well must be restarted after a shut-in period, the gas lift valves can be opened by reducing the control line pressure at the surface.

The control line of this invention is directly connected to the internal bellows/dome of the gas lift valve for tubing retrievable (conventional) method of valve installation. Side pocket mandrel installation has the control line connected to the mandrel which in turn transmits control pressure to the internal bellows/dome of the wireline gas lift valve, which has seals above and below. This control line invention can be used with injection pressure operated (IPO) or production pressure operated (PPO) valves. An option is an orifice at the deepest mandrel position that is not connected to the control line since it cannot close.

For this invention, charge gas (natural gas, nitrogen, carbon dioxide, air, or other fluid) supplied to the pneumatic tube control line would pass through a surface controller consisting of a pressure regulator and may include a desiccator or other devices. In addition, wellbore pressure sensors or distributed temperature sensing (DTS) lines could be installed independently of this invention.

OBJECT OF THE INVENTION

This invention with a control line connection from surface to the gas lift valve eliminates the sealed chamber and need for temperature knowledge since the internal valve pressure is adjusted at the surface to close the valve or to open the valve, which also eliminates the need to pull a valve out of the well. The pneumatic tube control line with charging gas is directly connected to a tubing retrievable (conventional) valve or is connected to the side pocket mandrel which transmits pressure between seals on the wireline retrievable valve. Control to close or open all gas lift valves is from the pressure regulator at the surface via the control line connected to each valve, either directly or to the side pocket mandrel with pressure transmission to the valve.

TECHNICAL FIELD OF THE INVENTION

This invention applies to oil, gas, or water supply wells in the upstream hydrocarbon resource industry and in the municipal or agricultural water supply industries. CPC class E21B covers obtaining oil, gas, water, or other materials from wells. Subclass 43 under well equipment or well maintenance covers obtaining fluids from wells, which includes 43/122 lifting well fluids and 43/123 gas lift. These methods for obtaining oil, gas, or water from wells includes wells that require artificial lift to produce reservoir fluid and may use gas lift as the preferred method. International class E21B 43/12 and 34/10 includes gas lift wells and valves.

PRIOR ART

The gas lift system that incorporates this invention is prior art with natural gas gathering from the production facility, compression, dehydration to remove water vapor, distribution to the various wells, measurement, and control of injection gas into each well for purposes of optimum allocation of gas. Options to natural gas from the production facility are processed natural gas from a plant, nitrogen, carbon dioxide, or air for water supply wells. Most installations in the prior art use valves that are pressure charged with nitrogen in the shop and sealed, which requires knowledge of the temperature in the wellbore at the depth of the valve when it is placed in operation because internal valve pressure varies with the change in temperature. Removal of the valve from the well to implement a different desired charge pressure requires a workover rig if tubing retrievable mandrels are used, or a wireline operation if side pocket mandrels are used.

DESCRIPTION OF THE PRIOR ART

The prior art for gas lift valve internal charge pressure uses depth related data for gas pressure in the annulus, production fluid pressure in the tubing, and temperature of each valve to calculate the internal charge pressure into the bellows/dome of the valve. The calculated pressure is applied to the valve in the shop and sealed, with nitrogen commonly utilized as the charging gas. The internal charge pressure into the bellows/dome of each valve is designed to close each in sequence from top to bottom, which requires a decline in casing pressure, observed at the surface, that enables each to close. This prior art design method reduces casing pressure which can limit depth of injection diminishing the effectiveness of gas lift and since each valve is pressure charged at surface and sealed, the valve must be pulled out of the well if a different internal charge pressure is desired. This design disadvantage of pulling valves to change the internal charge pressure is being addressed with a method of control from the surface.

Surface control options include electrical line or conduit and electrically controlled valve, hydraulic lines to a piston or bellows in the valve, acoustic link from valve to the surface, and this invention's pneumatic tube control line linking internal bellows/dome of the valve to a surface source of charge gas, which could be natural gas, nitrogen, carbon dioxide, air, or other fluid.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows the wellbore with tubing retrievable (conventional) gas lift valves, pneumatic tube control line linking the valves with the surface controller (consisting of the pressure regulator and other items), tubing, casing, wellhead, and pipeline to the production facility.

FIG. 2 shows the wellbore with side pocket mandrels connected to the pneumatic tube control line, with seals on the wireline retrievable valves, and the control line linking the valves with the surface controller (consisting of the pressure regulator and other items), tubing, casing, wellhead, and pipeline to the production facility.

FIG. 3 has a tubing retrievable (conventional) gas lift valve with detail showing the internal bellows/dome directly connected to the pneumatic tube control line.

FIG. 4 has a side pocket mandrel connected to the pneumatic tube control line with detail showing pressure transmitted to the internal bellows/dome between seals on the wireline retrievable valve.

DETAILED DESCRIPTION OF THE DRAWINGS

Gas lift installations use valves that are positioned on the tubing string at various depths based on the injection pressure in the casing, production fluid pressure in the tubing, and control (kill) fluid pressure used to maintain hydrostatic control of the well during wellbore equipment installation). This invention has a control line tube transmitting charge gas pressure from the surface directly to the valve.

FIG. 1 is a wellbore schematic with tubing retrievable gas lift mandrels and valves showing the high-pressure injection gas 1 passing through a gas meter 2, a control choke or regulator valve 3, into casing 4 by tubing 5 annulus to displace the control (kill) fluid out of the annulus, through each gas lift valve 6A to the tubing 5, until a deep injection point near the packer 7 is attained (multiple gas lift valves may be required but are not shown). The mixture of gas and tubing fluid is circulated to the wellhead 8, through piping (flowline) 9 and onward to the surface treating facility 10. Charge gas (natural gas, nitrogen, carbon dioxide, air, or other fluid) 11 supplied to a surface controller 12 consisting of a pressure regulator and may include a desiccator or other devices, goes into the pneumatic tube control line 13 directly connected to the bellows/dome of the gas lift valve 6A.

FIG. 2 is a wellbore schematic with side pocket gas lift mandrels and wireline retrievable valves showing the high-pressure injection gas 1 passing through a gas meter 2, a control choke or regulator valve 3, into casing 4 by tubing 5 annulus to displace the control (kill) fluid out of the annulus, through each gas lift valve 6B to the tubing 5, until a deep injection point near the packer 7 is attained (multiple gas lift valves may be required but are not shown). The mixture of gas and tubing fluid is circulated to the wellhead 8, through piping (flowline) 9 and onward to the surface treating facility 10. Charge gas (natural gas, nitrogen, carbon dioxide, air, or other fluid) 11 supplied to a surface controller 12 consisting of a pressure regulator and may include a desiccator or other devices, goes into the pneumatic tube control line 13 connected to the side pocket mandrel. Pressure is transmitted to the bellows/dome between seals on the wireline retrievable gas lift valve 6B.

FIG. 3 is an expanded view of the tubing retrievable (conventional) gas lift mandrel and valve described in FIG. 1 . Charge gas (natural gas, nitrogen, carbon dioxide, air, or other fluid) supplied through the pneumatic tube control line 13 is directly connected to the gas lift valve bellows/dome 14 and can force the valve 6A closed when pressure is raised by the surface pressure controller or opened to pass injection gas into the tubing 5 when pressure is relieved at the surface. The gas lift valve is any prior art valve supplied by any manufacturer of gas lift valves, absent the dill core (Schrader) valve. A check assembly (not shown) would be included with each gas lift valve.

FIG. 4 is an expanded view of the gas lift side pocket mandrel and wireline retrievable valve described in FIG. 2 . Charge gas (natural gas, nitrogen, carbon dioxide, air, or other fluid) supplied through the pneumatic tube control line 13 connected to the gas lift side pocket mandrel 15 is transmitted to the valve bellows/dome 16, located between seals 17 on the wireline retrievable valve. The charge gas through the control line 13 can force the valve 6B closed when pressure is raised by the surface pressure controller or opened to pass injection gas when pressure is relieved at the surface. The gas lift valve of this invention has seals 17 above and below passageways that transmit charge gas pressure to the bellows/dome 16 of the valve. The lower sections of the gas lift valve would be prior art supplied by any manufacturer of gas lift valves. A check assembly (not shown) would be included with each gas lift valve. 

1. A method to close or to open gas lift valves from the surface using a pneumatic tube control line to convey charge gas (natural gas, nitrogen, carbon dioxide, air, or other fluid) to the bellows/dome of the valve; this control method is applied to wells with one or multiple gas lift valves positioned on the tubing at depths desired to displace control (kill) fluids from the casing/tubing annulus and inside the tubing by enabling gas to pass from the annulus through an open valve to the tubing and circulating the fluid to the treating facility; surface control revealed by this disclosure enables the valve to be closed by raising control line charge pressure at the surface whereby the multiple valves are closed in sequence as surface charge gas pressure is increased; valves can be opened by reducing charge pressure at the surface; an option is a control line to each individual valve instead of one control line connected to all valves.
 2. The method of claim 1 is applied to tubing retrievable gas lift valves by directly connecting the charge gas pneumatic tube control line to the bellows/dome of any prior art gas lift valve from any manufacturer; the control line connects to the tail plug position of the gas lift valve, which does not contain a dill core (Schrader) valve, whereby increasing charge pressure inside the bellows/dome to close the valve and reducing charge pressure to open the valve; each valve is closed in sequence, from top to a depth near the packer, as control line charge pressure is raised whereby each valve at a deeper installation depth requires additional pressure; as control line pressure is reduced, the valves open in sequence from a depth near the packer to the top; an option is an orifice installed at the deepest point near the packer without a control line connection since it cannot close.
 3. The method of claim 1 to close or to open gas lift valves from the surface using a pneumatic tube control line to convey charge gas (natural gas, nitrogen, carbon dioxide, air, or other fluid) to the gas lift valve bellows/dome is modified for side pocket mandrels with wireline retrievable gas lift valves; the control line connects to the side pocket mandrel which transmits the charge pressure to the wireline retrievable gas lift valve; this disclosure requires seals above and below passageways on the wireline retrievable valve that access the bellows/dome area for application of charge gas from the control line connected to the side pocket mandrel whereby pressure is transmitted and contained within the seals of the wireline gas lift valve to the bellows/dome area to close the valve; reduced charge pressure will open the valve; the tail plug is installed but the dill core (Schrader) valve is not required.
 4. Claim 3 modifies the upper section of the wireline retrievable gas lift valve that includes the bellows/dome to include slots that transmit pressure from the control line attached to the side pocket mandrel to the dome of the valve, but the lower section can be any prior art gas lift valve from any manufacturer.
 5. Claim 1 and claim 3 eliminate the requirement to pull valves from the well to reset a sealed valve charge pressure if a different setting is desired, because this invention provides surface control of charge pressure; claim 1 and claim 3 eliminate the need for a valve temperature at valve depth since this invention does not have a sealed chamber where pressure is dependent on the temperature; with this disclosure, charge pressure at surface can be adjusted to close or to open a gas lift valve when transmitted through the pneumatic tube control line to each valve. 